Methods and devices for optically determining a characteristic of a substance

ABSTRACT

Optical computing devices are disclosed. One exemplary optical computing device includes an electromagnetic radiation source configured to optically interact with a sample and at least two integrated computational elements. The at least two integrated computational elements are configured to produce optically interacted light and further configured to be associated with a characteristic of the sample. The optical computing device further includes a first detector arranged to receive the optically interacted light from the at least two integrated computational elements and thereby generate a first signal corresponding to the characteristic of the sample.

BACKGROUND

The present invention generally relates to systems and methods ofoptical computing and, more specifically, to systems and methods ofdetermining a particular characteristic of a substance using two or moreintegrated computational elements.

Spectroscopic techniques for measuring various characteristics ofmaterials are well known and are routinely used under laboratoryconditions. In some cases, these spectroscopic techniques can be carriedout without using an involved sample preparation. It is more common,however, to carry out various sample preparation procedures beforeconducting the analysis. Reasons for conducting sample preparationprocedures can include, for example, removing interfering backgroundmaterials from the analyte of interest, converting the analyte ofinterest into a chemical form that can be better detected by a chosenspectroscopic technique, and adding standards to improve the accuracy ofquantitative measurements. Thus, there is usually a delay in obtainingan analysis due to sample preparation time, even discounting the transittime of transporting the sample to a laboratory.

Although spectroscopic techniques can, at least in principle, beconducted at a job site, such as a well site, or in a process, theforegoing concerns regarding sample preparation times can still apply.Furthermore, the transitioning of spectroscopic instruments from alaboratory into a field or process environment can be expensive andcomplex. Reasons for these issues can include, for example, the need toovercome inconsistent temperature, humidity, and vibration encounteredduring field use. Furthermore, sample preparation, when required, can bedifficult under field analysis conditions. The difficulty of performingsample preparation in the field can be especially problematic in thepresence of interfering materials, which can further complicateconventional spectroscopic analyses. Quantitative spectroscopicmeasurements can be particularly challenging in both field andlaboratory settings due to the need for precision and accuracy in samplepreparation and spectral interpretation.

SUMMARY OF THE INVENTION

The present invention generally relates to systems and methods ofoptical computing and, more specifically, to systems and methods ofdetermining a particular characteristic of a substance using two or moreintegrated computational elements.

In one embodiment, the present invention provides a device including anelectromagnetic radiation source configured to optically interact with asample and at least two integrated computational elements. The at leasttwo integrated computational elements may be configured to produceoptically interacted light and may further be configured to beassociated with a characteristic of the sample. The device may alsoinclude at least one detector arranged to receive the opticallyinteracted light from the at least two integrated computational elementsand thereby generate a first signal and a second signal. The first andsecond signals may then be computationally combined to determine thecharacteristic of the sample.

In another embodiment, a method of determining a characteristic of asample is disclosed. The method may include optically interacting anelectromagnetic radiation source with the sample and at least twointegrated computational elements, and producing optically interactedlight from the at least two integrated computational elements. The atleast two integrated computational elements may each be configured to beassociated with the characteristic of the sample. The method may alsoinclude receiving with at least one detector the optically interactedlight from the at least two integrated computational elements, therebygenerating a first signal and a second signal, and computationallycombining the first and second signals to determine the characteristicof the sample.

In another aspect of the disclosure, another device is disclosed and mayinclude an electromagnetic radiation source configured to opticallyinteract with a sample and at least two integrated computationalelements. The at least two integrated computational elements may beconfigured to produce optically interacted light and may further beconfigured to be associated with a characteristic of the sample. Thedevice may also include a first detector arranged to receive theoptically interacted light from the at least two integratedcomputational elements and thereby generate a first signal correspondingto the characteristic of the sample.

In yet another aspect of the disclosure, another method of determining acharacteristic of a sample is disclosed. The method may includeoptically interacting an electromagnetic radiation source with a sampleand at least two integrated computational elements, and producingoptically interacted light from the at least two integratedcomputational elements. The at least two integrated computationalelements may each be configured to be associated with the characteristicof the sample. The method may also include receiving with at least onedetector the optically interacted light from the at least two integratedcomputational elements, thereby generating a first signal correspondingto the characteristic of the sample.

In yet another aspect of the disclosure, another device is disclosed andmay include at least two integrated computational elements configured toreceive electromagnetic radiation emitted from a sample and produceoptically interacted light. The at least two integrated computationalelements may be configured to be associated with a characteristic of thesample. The device may also include at least one detector arranged toreceive the optically interacted light from the at least two integratedcomputational elements and thereby generate a first signal and a secondsignal. The first and second signals may be subsequently computationallycombined to determine the characteristic of the sample.

In yet another aspect of the disclosure, another method of determining acharacteristic of a sample is disclosed. The method may includeoptically interacting electromagnetic radiation radiated from the samplewith at least two integrated computational elements, and producingoptically interacted light from the at least two integratedcomputational elements. The at least two integrated computationalelements may each be configured to be associated with the characteristicof the sample. The method may also include receiving with at least onedetector the optically interacted light from the at least two integratedcomputational elements, thereby generating a first signal correspondingto the characteristic of the sample.

The features and advantages of the present invention will be readilyapparent to one having ordinary skill in the art upon a reading of thedescription of the preferred embodiments that follows.

BRIEF DESCRIPTION OF THE DRAWINGS

The following figures are included to illustrate certain aspects of thepresent invention, and should not be viewed as exclusive embodiments.The subject matter disclosed is capable of considerable modification,alteration, and equivalents in form and function, as will occur to onehaving ordinary skill in the art and having the benefit of thisdisclosure.

FIG. 1 illustrates an exemplary integrated computation element,according to one or more embodiments.

FIG. 2 illustrates a block diagram non-mechanistically illustrating howan optical computing device distinguishes electromagnetic radiationrelated to a characteristic of interest from other electromagneticradiation, according to one or more embodiments.

FIG. 3 illustrates an exemplary optical computing device, according toone or more embodiments.

FIG. 4 illustrates a graph indicating the detection of a characteristicof interest in a sample using one or more integrated computationalelements.

FIG. 5 illustrates another graph indicating the detection of acharacteristic of interest in a sample using one or more integratedcomputational elements.

FIG. 6 illustrates another exemplary optical computing device, accordingto one or more embodiments.

FIG. 7 illustrates another exemplary optical computing device, accordingto one or more embodiments.

FIG. 8 illustrates another exemplary optical computing device, accordingto one or more embodiments.

FIGS. 9a, 9b, and 9c illustrate other exemplary optical computingdevices, according to one or more embodiments.

FIG. 10 illustrates another exemplary optical computing device,according to one or more embodiments.

FIG. 11 illustrates another exemplary optical computing device,according to one or more embodiments.

DETAILED DESCRIPTION

The present invention generally relates to systems and methods ofoptical computing and, more specifically, to systems and methods ofdetermining a particular characteristic of a substance using two or moreintegrated computational elements.

Embodiments described herein include various configurations of opticalcomputing devices, also commonly referred to as “opticoanalyticaldevices.” The various embodiments of the disclosed optical computingdevices may be suitable for use in the oil and gas industry. Forexample, embodiments disclosed herein provide systems and/or devicescapable of providing a relatively low cost, rugged, and accurate systemfor monitoring petroleum quality for the purpose of optimizingdecision-making at a well site to facilitate the efficient management ofhydrocarbon production. Embodiments disclosed herein may also be usefulin determining concentrations of various analytes of interest in anyfluid present within a wellbore. It will be appreciated, however, thatthe various disclosed systems and devices are equally applicable toother technology fields including, but not limited to, the food and drugindustry, industrial applications, mining industries, or any field whereit may be advantageous to determine in real-time the concentrations of aspecific characteristic or analyte of interest of a compound ormaterial.

As used herein, the term “fluid” refers to any substance that is capableof flowing, including particulate solids, liquids, gases, slurries,emulsions, powders, muds, glasses, combinations thereof, and the like.In some embodiments, the fluid can be an aqueous fluid, including wateror the like. In some embodiments, the fluid can be a non-aqueous fluid,including organic compounds, more specifically, hydrocarbons, oil, arefined component of oil, petrochemical products, and the like. In someembodiments, the fluid can be a treatment fluid or a formation fluid.Fluids can include various flowable mixtures of solids, liquids and/orgases. Illustrative gases that can be considered fluids according to thepresent embodiments include, for example, air, nitrogen, carbon dioxide,argon, helium, hydrogen disulfide, mercaptan, thiophene, methane,ethane, butane, and other hydrocarbon gases, combinations thereof and/orthe like.

As used herein, the term “characteristic” refers to a chemical,mechanical, or physical property of a substance. A characteristic of asubstance may include a quantitative value of one or more chemicalcomponents therein. Such chemical components may be referred to hereinas “analytes.” Illustrative characteristics of a substance that can bemonitored with the optical computing devices disclosed herein caninclude, for example, chemical composition e.g., identity andconcentration, in total or of individual components, impurity content,pH, viscosity, density, ionic strength, total dissolved solids, saltcontent, porosity, opacity, bacteria content, combinations thereof, andthe like.

As used herein, the term “electromagnetic radiation” refers to radiowaves, microwave radiation, infrared and near-infrared radiation,visible light, ultraviolet light, X-ray radiation and gamma rayradiation.

As used herein, the term “optical computing device” refers to an opticaldevice that is configured to receive an input of electromagneticradiation from a substance or sample of the substance, and produce anoutput of electromagnetic radiation from a processing element. Theprocessing element may be, for example, an integrated computationalelement. The electromagnetic radiation emanating from the processingelement is changed in some way so as to be readable by a detector, suchthat an output of the detector can be correlated to at least onecharacteristic of the substance. The output of electromagnetic radiationfrom the processing element can be reflected electromagnetic radiation,transmitted electromagnetic radiation, and/or dispersed electromagneticradiation. As will be appreciated by those skilled in the art, whetherreflected or transmitted electromagnetic radiation is analyzed by thedetector may be dictated by the structural parameters of the opticalcomputing device as well as other considerations known to those skilledin the art. In addition, emission and/or scattering of the substance,for example via fluorescence, luminescence, Raman scattering, and/orRaleigh scattering can also be monitored by the optical computingdevices.

As used herein, the term “optically interact” or variations thereofrefers to the reflection, transmission, scattering, diffraction, orabsorption of electromagnetic radiation either on, through, or from oneor more processing elements, such as integrated computational elements.Accordingly, optically interacted light refers to light that has beenreflected, transmitted, scattered, diffracted, or absorbed by, emitted,or re-radiated, for example, using the integrated computationalelements, but may also apply to interaction with a sample substance.

As used herein, the term “sample,” or variations thereof, refers to atleast a portion of a substance of interest to be tested or otherwiseevaluated using the optical computing devices described herein. Thesample includes the characteristic of interest, as defined above, andmay be any fluid, as defined herein, or otherwise any solid substance ormaterial such as, but not limited to, rock formations, concrete, othersolid surfaces, etc.

At the very least, the exemplary optical computing devices disclosedherein will each include an electromagnetic radiation source, at leasttwo processing elements (e.g., integrated computational elements), andat least one detector arranged to receive optically interacted lightfrom the at least two processing elements. As disclosed below, however,in at least one embodiment, the electromagnetic radiation source may beomitted and instead the electromagnetic radiation may be derived fromthe substance or the sample of the substance itself. In someembodiments, the exemplary optical computing devices may be specificallyconfigured for detecting, analyzing, and quantitatively measuring aparticular characteristic or analyte of interest of a given sample orsubstance. In other embodiments, the exemplary optical computing devicesmay be general purpose optical devices, with post-acquisition processing(e.g., through computer means) being used to specifically detect thecharacteristic of the sample.

In some embodiments, suitable structural components for the exemplaryoptical computing devices disclosed herein are described in commonlyowned U.S. Pat. Nos. 6,198,531; 6,529,276; 7,123,844; 7,834,999;7,911,605, 7,920,258, and 8,049,881, each of which is incorporatedherein by reference in its entirety, and U.S. patent application Ser.No. 12/094,460 (U.S. Pat. App. Pub. No. 2009/0219538); and Ser. No.12/094,465 (U.S. Pat. App. Pub. No. 2009/0219539), each of which is alsoincorporated herein by reference in its entirety. As will beappreciated, variations of the structural components of the opticalcomputing devices described in the above-referenced patents and patentapplications may be suitable, without departing from the scope of thedisclosure, and therefore, should not be considered limiting to thevarious embodiments disclosed herein.

The optical computing devices described in the foregoing patents andpatent applications combine the advantage of the power, precision andaccuracy associated with laboratory spectrometers, while being extremelyrugged and suitable for field use. Furthermore, the optical computingdevices can perform calculations (analyses) in real-time or nearreal-time without the need for sample processing. In this regard, theoptical computing devices can be specifically configured to detect andanalyze particular characteristics and/or analytes of interest. As aresult, interfering signals are discriminated from those of interest ina sample by appropriate configuration of the optical computing devices,such that the optical computing devices provide a rapid responseregarding the characteristics of the sample as based on the detectedoutput. In some embodiments, the detected output can be converted into avoltage that is distinctive of the magnitude of the characteristic beingmonitored in the sample. The foregoing advantages and others make theoptical computing devices, and their variations generally describedbelow, particularly well suited for field and downhole use.

The exemplary optical computing devices described herein can beconfigured to detect not only the composition and concentrations of amaterial or mixture of materials, but they also can be configured todetermine physical properties and other characteristics of the materialas well, based on their analysis of the electromagnetic radiationreceived from the sample. For example, the optical computing devices canbe configured to determine the concentration of an analyte and correlatethe determined concentration to a characteristic of a substance by usingsuitable processing means. As will be appreciated, the optical computingdevices may be configured to detect as many characteristics or analytesas desired in a given sample. All that is required to accomplish themonitoring of multiple characteristics or analytes is the incorporationof suitable processing and detection means within the optical computingdevice for each characteristic or analyte. In some embodiments, theproperties of a substance can be a combination of the properties of theanalytes therein (e.g., a linear, non-linear, logarithmic, and/orexponential combination). Accordingly, the more characteristics andanalytes that are detected and analyzed using the exemplary opticalcomputing devices, the more accurately the properties of the givensample can be determined.

The optical computing devices disclosed herein utilize electromagneticradiation to perform calculations, as opposed to the hardwired circuitsof conventional electronic processors. When electromagnetic radiationinteracts with a substance, unique physical and chemical informationabout the substance may be encoded in the electromagnetic radiation thatis reflected from, transmitted through, or radiated from the sample.This information is often referred to as the substance's spectral“fingerprint.” At least in some embodiments, the exemplary opticalcomputing devices disclosed herein are capable of extracting theinformation of the spectral fingerprint of multiple characteristics oranalytes within a substance and converting that information into adetectable output regarding the overall properties of a sample. That is,through suitable configurations of the exemplary optical computingdevices, electromagnetic radiation associated with characteristics oranalytes of interest in a substance can be separated fromelectromagnetic radiation associated with all other components of asample in order to estimate the sample's properties in real-time or nearreal-time.

The at least two processing elements used in the exemplary opticalcomputing devices described herein may be characterized as integratedcomputational elements (ICE). The ICE are capable of distinguishingelectromagnetic radiation related to the characteristic or analyte ofinterest from electromagnetic radiation related to other components of asample substance. Referring to FIG. 1, illustrated is an exemplary ICE100 suitable for use in the various optical computing devices describedherein, according to one or more embodiments. As illustrated, the ICE100 may include a plurality of alternating layers 102 and 104, such assilicon (Si) and SiO₂ (quartz), respectively. In general, these layersconsist of materials whose index of refraction is high and low,respectively. Other examples might include niobia and niobium, germaniumand germania, MgF, SiO, and other high and low index materials known inthe art. The layers 102, 104 may be strategically deposited on anoptical substrate 106. In some embodiments, the optical substrate 106 isBK-7 optical glass. In other embodiments, the optical substrate 106 maybe other types of optical substrates, such as quartz, sapphire, silicon,germanium, zinc selenide, zinc sulfide, or various plastics such aspolycarbonate, polymethylmethacrylate (PMMA), polyvinylchloride (PVC),diamond, ceramics, combinations thereof, and the like. At the oppositeend (e.g., opposite the optical substrate 106), the ICE 100 may includea layer 108 that is generally exposed to the environment of the deviceor installation. The number of layers 102, 104 and the thickness of eachlayer 102, 104 are determined from the spectral attributes acquired froma spectroscopic analysis of a characteristic of the sample substanceusing a conventional spectroscopic instrument. The spectrum of interestof a given characteristic of a sample typically includes any number ofdifferent wavelengths. It should be understood that the exemplary ICE100 in FIG. 1 does not in fact represent any particular characteristicof a given sample, but is provided for purposes of illustration only.Consequently, the number of layers 102, 104 and their relativethicknesses, as shown in FIG. 1, bear no correlation to any particularcharacteristic of a given sample. Nor are the layers 102, 104 and theirrelative thicknesses necessarily drawn to scale, and therefore shouldnot be considered limiting of the present disclosure. Moreover, thoseskilled in the art will readily recognize that the materials that makeup each layer 102, 104 (i.e., Si and SiO₂) may vary, depending on theapplication, cost of materials, and/or applicability of the material tothe sample substance.

In some embodiments, the material of each layer 102, 104 can be doped ortwo or more materials can be combined in a manner to achieve the desiredoptical characteristic. In addition to solids, the exemplary ICE 100 mayalso contain liquids and/or gases, optionally in combination withsolids, in order to produce a desired optical characteristic. In thecase of gases and liquids, the ICE 100 can contain a correspondingvessel (not shown), which houses the gases or liquids. Exemplaryvariations of the ICE 100 may also include holographic optical elements,gratings, piezoelectric, light pipe, digital light pipe (DLP), and/oracousto-optic elements, for example, that can create transmission,reflection, and/or absorptive properties of interest.

The multiple layers 102, 104 exhibit different refractive indices. Byproperly selecting the materials of the layers 102, 104 and theirrelative spacing, the exemplary ICE 100 may be configured to selectivelypass/reflect/refract predetermined fractions of electromagneticradiation at different wavelengths. Each wavelength is given apredetermined weighting or loading factor. The thicknesses and spacingof the layers 102, 104 may be determined using a variety ofapproximation methods from the spectrograph of the character or analyteof interest. These methods may include inverse Fourier transform (IFT)of the optical transmission spectrum and structuring the ICE 100 as thephysical representation of the IFT. The approximations convert the IFTinto a structure based on known materials with constant refractiveindices. Further information regarding the structures and design ofexemplary integrated computational elements (also referred to asmultivariate optical elements) is provided in Applied Optics, Vol. 35,pp. 5484-5492 (1996) and Vol. 129, pp. 2876-2893, which is herebyincorporated by reference.

The weightings that the layers 102, 104 of the ICE 100 apply at eachwavelength are set to the regression weightings described with respectto a known equation, or data, or spectral signature. Briefly, the ICE100 may be configured to perform the dot product of the input light beaminto the ICE 100 and a desired loaded regression vector represented byeach layer 102, 104 for each wavelength. As a result, the output lightintensity of the ICE 100 is related to the characteristic or analyte ofinterest. Further details regarding how the exemplary ICE 100 is able todistinguish and process electromagnetic radiation related to thecharacteristic or analyte of interest are described in U.S. Pat. Nos.6,198,531; 6,529,276; and 7,920,258, previously incorporated herein byreference.

Referring now to FIG. 2, illustrated is a block diagram thatnon-mechanistically illustrates how an optical computing device 200 isable to distinguish electromagnetic radiation related to acharacteristic of a sample from other electromagnetic radiation. Asshown in FIG. 2, after being illuminated with incident electromagneticradiation, a sample 202 containing an analyte of interest (e.g., acharacteristic of the sample) produces an output of electromagneticradiation (e.g., sample-interacted light), some of which iselectromagnetic radiation 204 corresponding to the characteristic oranalyte of interest and some of which is background electromagneticradiation 206 corresponding to other components or characteristics ofthe sample 202. Although not specifically shown, one or more spectralelements may be employed in the device 200 in order to restrict theoptical wavelengths and/or bandwidths of the system and therebyeliminate unwanted electromagnetic radiation existing in wavelengthregions that have no importance. Such spectral elements can be locatedanywhere along the optical train, but are typically employed directlyafter the light source, which provides the initial electromagneticradiation. Various configurations and applications of spectral elementsin optical computing devices may be found in commonly owned U.S. Pat.Nos. 6,198,531; 6,529,276; 7,123,844; 7,834,999; 7,911,605, 7,920,258,8,049,881, and U.S. patent application Ser. No. 12/094,460 (U.S. Pat.App. Pub. No. 2009/0219538); Ser. No. 12/094,465 (U.S. Pat. App. Pub.No. 2009/0219539), incorporated herein by reference, as indicated above.

The beams of electromagnetic radiation 204, 206 impinge upon the opticalcomputing device 200, which contains an exemplary ICE 208 therein. TheICE 208 may be configured to produce optically interacted light, forexample, transmitted optically interacted light 210 and reflectedoptically interacted light 214. In at least one embodiment, the ICE 208may be configured to distinguish the electromagnetic radiation 204 fromthe background electromagnetic radiation 206.

The transmitted optically interacted light 210, which may be related tothe characteristic or analyte of interest, may be conveyed to a detector212 for analysis and quantification. In some embodiments, the detector212 is configured to produce an output signal in the form of a voltagethat corresponds to the particular characteristic of the sample 202. Inat least one embodiment, the signal produced by the detector 212 and theconcentration of the characteristic of the sample 202 may be directlyproportional. In other embodiments, the relationship may be a polynomialfunction, an exponential function, and/or a logarithmic function. Thereflected optically interacted light 214, which may be related to thecharacteristic and other components of sample 202, can be directed awayfrom detector 212. In alternative configurations, the ICE 208 may beconfigured such that the reflected optically interacted light 214 can berelated to the analyte of interest, and the transmitted opticallyinteracted light 210 can be related to other components of the sample202.

In some embodiments, a second detector 216 can be present and arrangedto detect the reflected optically interacted light 214. In otherembodiments, the second detector 216 may be arranged to detect theelectromagnetic radiation 204, 206 derived from the sample 202 orelectromagnetic radiation directed toward or before the sample 202.Without limitation, the second detector 216 may be used to detectradiating deviations stemming from an electromagnetic radiation source(not shown), which provides the electromagnetic radiation (i.e., light)to the device 200. For example, radiating deviations can include suchthings as, but not limited to, intensity fluctuations in theelectromagnetic radiation, interferent fluctuations (e.g., dust or otherinterferents passing in front of the electromagnetic radiation source),coatings on windows included with the optical computing device 200,combinations thereof, or the like. In some embodiments, a beam splitter(not shown) can be employed to split the electromagnetic radiation 204,206, and the transmitted or reflected electromagnetic radiation can thenbe directed to one or more ICE 208. That is, in such embodiments, theICE 208 does not function as a type of beam splitter, as depicted inFIG. 2, and the transmitted or reflected electromagnetic radiationsimply passes through the ICE 208, being computationally processedtherein, before travelling to the detector 212.

The characteristic(s) of the sample being analyzed using the opticalcomputing device 200 can be further processed computationally to provideadditional characterization information about the substance beinganalyzed. In some embodiments, the identification and concentration ofeach analyte in the sample 202 can be used to predict certain physicalcharacteristics of the sample 202. For example, the bulk characteristicsof a sample 202 can be estimated by using a combination of theproperties conferred to the sample 202 by each analyte.

In some embodiments, the concentration of each analyte or the magnitudeof each characteristic determined using the optical computing device 200can be fed into an algorithm operating under computer control. Thealgorithm may be configured to make predictions on how thecharacteristics of the sample 202 change if the concentrations of theanalytes are changed relative to one another. In some embodiments, thealgorithm can produce an output that is readable by an operator who canmanually take appropriate action, if needed, based upon the output. Insome embodiments, the algorithm can take proactive process control byautomatically adjusting the characteristics of, for example, a treatmentfluid being introduced into a subterranean formation or by halting theintroduction of the treatment fluid in response to an out of rangecondition.

The algorithm can be part of an artificial neural network configured touse the concentration of each detected analyte in order to evaluate thecharacteristic(s) of the sample 202 and predict how to modify the sample202 in order to alter its properties in a desired way. Illustrative butnon-limiting artificial neural networks are described in commonly ownedU.S. patent application Ser. No. 11/986,763 (U.S. Patent ApplicationPublication 2009/0182693), which is incorporated herein by reference. Itis to be recognized that an artificial neural network can be trainedusing samples having known concentrations, compositions, and/orproperties, thereby generating a virtual library. As the virtual libraryavailable to the artificial neural network becomes larger, the neuralnetwork can become more capable of accurately predicting thecharacteristics of a sample having any number of analytes presenttherein. Furthermore, with sufficient training, the artificial neuralnetwork can more accurately predict the characteristics of the sample,even in the presence of unknown analytes.

It is recognized that the various embodiments herein directed tocomputer control and artificial neural networks, including variousblocks, modules, elements, components, methods, and algorithms, can beimplemented using computer hardware, software, combinations thereof, andthe like. To illustrate this interchangeability of hardware andsoftware, various illustrative blocks, modules, elements, components,methods and algorithms have been described generally in terms of theirfunctionality. Whether such functionality is implemented as hardware orsoftware will depend upon the particular application and any imposeddesign constraints. For at least this reason, it is to be recognizedthat one of ordinary skill in the art can implement the describedfunctionality in a variety of ways for a particular application.Further, various components and blocks can be arranged in a differentorder or partitioned differently, for example, without departing fromthe scope of the embodiments expressly described.

Computer hardware used to implement the various illustrative blocks,modules, elements, components, methods, and algorithms described hereincan include a processor configured to execute one or more sequences ofinstructions, programming stances, or code stored on a non-transitory,computer-readable medium. The processor can be, for example, a generalpurpose microprocessor, a microcontroller, a digital signal processor,an application specific integrated circuit, a field programmable gatearray, a programmable logic device, a controller, a state machine, agated logic, discrete hardware components, an artificial neural network,or any like suitable entity that can perform calculations or othermanipulations of data. In some embodiments, computer hardware canfurther include elements such as, for example, a memory (e.g., randomaccess memory (RAM), flash memory, read only memory (ROM), programmableread only memory (PROM), erasable read only memory (EPROM)), registers,hard disks, removable disks, CD-ROMS, DVDs, or any other like suitablestorage device or medium.

Executable sequences described herein can be implemented with one ormore sequences of code contained in a memory. In some embodiments, suchcode can be read into the memory from another machine-readable medium.Execution of the sequences of instructions contained in the memory cancause a processor to perform the process steps described herein. One ormore processors in a multi-processing arrangement can also be employedto execute instruction sequences in the memory. In addition, hard-wiredcircuitry can be used in place of or in combination with softwareinstructions to implement various embodiments described herein. Thus,the present embodiments are not limited to any specific combination ofhardware and/or software.

As used herein, a machine-readable medium will refer to any medium thatdirectly or indirectly provides instructions to a processor forexecution. A machine-readable medium can take on many forms including,for example, non-volatile media, volatile media, and transmission media.Non-volatile media can include, for example, optical and magnetic disks.Volatile media can include, for example, dynamic memory. Transmissionmedia can include, for example, coaxial cables, wire, fiber optics, andwires that form a bus. Common forms of machine-readable media caninclude, for example, floppy disks, flexible disks, hard disks, magnetictapes, other like magnetic media, CD-ROMs, DVDs, other like opticalmedia, punch cards, paper tapes and like physical media with patternedholes, RAM, ROM, PROM, EPROM and flash EPROM.

In some embodiments, the data collected using the optical computingdevices can be archived along with data associated with operationalparameters being logged at a job site. Evaluation of job performance canthen be assessed and improved for future operations or such informationcan be used to design subsequent operations. In addition, the data andinformation can be communicated (wired or wirelessly) to a remotelocation by a communication system (e.g., satellite communication orwide area network communication) for further analysis. The communicationsystem can also allow remote monitoring and operation of a process totake place. Automated control with a long-range communication system canfurther facilitate the performance of remote job operations. Inparticular, an artificial neural network can be used in some embodimentsto facilitate the performance of remote job operations. That is, remotejob operations can be conducted automatically in some embodiments. Inother embodiments, however, remote job operations can occur under directoperator control, where the operator is not at the job site.

Referring now to FIG. 3, illustrated is an exemplary optical computingdevice 300, according to one or more embodiments. The device 300 may besomewhat similar to the optical computing device 200 described above inFIG. 2, and therefore may be best understood with reference thereto. Thedevice 300 may include at least two ICEs, illustrated as a first ICE 302and a second ICE 304. The first and second ICE 302, 304 may be generallysimilar in construction to the ICE 100 described above with reference toFIG. 1, but may also vary from each other depending on the application,as will be better understood from the discussion below. In operation,the first and second ICE 302, 304 may enhance sensitivities anddetection limits of the device 300 beyond what would be otherwisecapable with a single ICE design. As will be appreciated, and discussedin greater detail below, two or more ICEs may be used in alternativeconfigurations or embodiments, without departing from the scope of thedisclosure.

In one embodiment, the first and second ICE 302, 304 may be configuredto be associated with a particular characteristic of a sample 306. Inother words, the first and second ICE 302, 304 may be especiallydesigned in their respective layers, thicknesses, and materials so as tocorrespond with the spectral attributes associated with thecharacteristic of interest. Each of the first and second ICE 302, 304,however, may be designed entirely different from each other, therebyapproximating or otherwise mimicking the regression vector of thecharacteristic in entirely different ways.

In other embodiments, however, one or both of the first and second ICE302, 304 may not necessarily be configured to be associated with aparticular characteristic of the sample 306, but instead may be entirelyor substantially disassociated with the characteristic of interest. Forexample, manufacturing an ICE can be a very complex and intricateprocess. In addition, when an ICE is manufactured specifically to matchor mimic the regression vector of a characteristic of interest, thisprocess can become even more complicated. As a result, it is common toproduce non-predictive, or poorly made ICE that, when tested, fail toaccurately or even remotely be associated with the characteristic ofinterest. In some cases, these non-predictive ICE may return anarbitrary regression vector when tested or otherwise exhibit anarbitrary transmission function. In other cases, the non-predictive ICEmay be considered “substantially” disassociated with the characteristicof interest in that the ICE only slightly mimics the regression vectorof the characteristic, but is nonetheless considered non-predictive. Inyet other cases, the non-predictive ICE may return a regression vectorthat closely mimics another characteristic of the substance beingtested, but not the characteristic of interest.

As shown, the first and second ICE 302, 304 may be coupled together soas to form a generally monolithic structure. For example, the first andsecond IC 302, 304 may be mechanically or adhesively attached. In otherembodiments, however, the first and second ICE 302, 304 may be arrangedin series. For example, optically interacted light generated by thefirst ICE 302 may be received by the second ICE 304 in embodiments wherethe first and second ICE 302, 304 are separated in series by a nominaldistance. The nominal distance can be anywhere from a few microns toseveral feet, and even further, depending on the size of the opticalcomputing device 300. In at least one embodiment, the first ICE 302 mayreflect optically interacted light to be subsequently received by thesecond ICE 304. In other embodiments, however, the first ICE 302 maytransmit (i.e., allow to pass through) optically interacted light to besubsequently received by the second ICE 304. It should also berecognized that any of the ensuing configurations for optical computingdevices can be used in combination with a series configuration in any ofthe present embodiments.

In FIG. 3, an electromagnetic radiation source 308 may be configured toemit or otherwise generate electromagnetic radiation 310. Theelectromagnetic radiation source 308 may be any device capable ofemitting or generating electromagnetic radiation, as defined herein. Insome embodiments, the electromagnetic radiation source 308 is a lightbulb, light emitting device (LED), laser, blackbody, photonic crystal,or X-Ray source, or the like. In one embodiment, the electromagneticradiation 310 may be configured to optically interact with the sample306 and generate sample-interacted light 312 directed to the first andsecond ICE 302, 304. The sample 306 may be any fluid, as defined herein,or otherwise any solid substance or material such as, but not limitedto, rock formations, concrete, or other solid surfaces. While FIG. 3shows the electromagnetic radiation 310 as passing through the sample306 to produce the sample-interacted light 312, it is also contemplatedherein to reflect the electromagnetic radiation 310 off of the sample306, such as in the case of a sample 306 that is translucent, opaque, orsolid, and equally generate the sample-interacted light 312.

In the illustrated embodiment, the sample-interacted light 312 may beconfigured to optically interact with the first and second ICE 302, 304and pass therethrough, thereby producing optically interacted light 314that is directed to a detector 316. It should be noted that while FIG. 3shows the sample-interacted light 312 as passing through the first andsecond ICE 302, 304 in order to generate the optically interacted light314, it is also contemplated herein to reflect the sample-interactedlight 312 off of the first and second ICE 302, 304 and equally generatethe beam of optically interacted light 314. The detector 316 may bearranged to receive the optically interacted light 314 from the firstand second ICE 302, 304 and generate a signal that corresponds to theparticular characteristic of the sample 306. Similar to the detector 212of FIG. 2, the detector 316 may be any device capable of detectingelectromagnetic radiation, and may be generally characterized as anoptical transducer. For example, the detector 316 may be, but is notlimited to, a thermal detector such as a thermopile or photoacousticdetector, a semiconductor detector, a piezo-electric detector, chargecoupled device (CCD) detector, video or array detector, split detector,photon detector (such as a photomultiplier tube), photodiodes, and/orcombinations thereof, or the like, or other detectors known to thoseskilled in the art.

In at least one embodiment, the device 300 may include a second detector318 arranged to receive and detect reflected optically interacted light320 and thereby output a compensating signal 322. The second detector318 may be substantially similar to the second detector 216 describedabove with reference to FIG. 2. Accordingly, the second detector 318 maydetect radiating deviations stemming from the electromagnetic radiationsource 308. In some embodiments, the second detector 318 may be arrangedto receive a portion of the sample-interacted light 312 instead of thereflected optically interacted light 320, and thereby compensate forelectromagnetic radiating deviations stemming from the electromagneticradiation source 308. In yet other embodiments, the second detector 318may be arranged to receive a portion of the electromagnetic radiation310 instead of the reflected optically interacted light 320, and therebylikewise compensate for electromagnetic radiating deviations stemmingfrom the electromagnetic radiation source 308.

We have discovered, in at least some embodiments, that using acombination of two or more ICE for the detection of a singlecharacteristic of interest may result in substantially improved overalldetection performance. This discovery was entirely unexpected. Forexample, U.S. Pat. No. 7,911,605 and U.S. Pat. Pub. No. 2010/0153048,incorporated herein by reference, describe in great detail how to designand build single ICE elements with optimal performance characteristics.Using the methods described in these references, literally thousands andhundreds of thousands of individual unique designs are created andoptimized for performance, thereby exhausting the optimal solution spaceavailable and yielding the best solutions possible. Those skilled in theart will readily recognize that ICE elements can be particularlysensitive to small changes in their optical characteristics. Thus, anymodification of the optical characteristic (e.g., changes made to theparticular transmission function) with additional ICE elements, could beconsidered as degrading the performance of the optical computing device,and in most cases, quite rapidly with only small changes. Indeed, it hasbeen discovered that some combinations of ICE components do degrade theoverall performance of the optical computing device.

However, we have unexpectedly discovered that, in one or moreembodiments, some preferred combinations of ICE can enhance performanceand sensitivities. It has further been discovered that theseenhancements are not minor adjustments or improvements, but instead maybe able to enhance performance in what may be viewed as a dramatic wayinvolving factors and/or orders of magnitude of improvement. It has yetfurther been discovered that such performance enhancements may beobtained without substantial compromise or trade-off of other importantcharacteristics. In many embodiments, as briefly discussed above, eachof the first and second ICE may be configured to be associated with theparticular characteristic of the sample and serve to enhancesensitivities and detection limits of the device 300 beyond what wouldbe otherwise capable with a single ICE design. However, we haveunexpectedly discovered that embodiments where one or both of the firstand second ICE are configured to be disassociated (or mainlydisassociated) with the particular characteristic of the sample 306 maynonetheless serve to enhance the performance of the device 300 ascompared to applications employing a single ICE to detect the samecharacteristic.

For example, referring to FIG. 4, illustrated is a graph 400 indicatingthe detection of a particular characteristic in a sample using one ormore ICE components. It will be appreciated that the graph 400 and thedata presented therein are merely used to facilitate a betterunderstanding of the present disclosure, and in no way should the theybe read to limit or define the scope of the invention. The graph 400indicates the detection of hydrogen disulfide (H₂S) gas as thecharacteristic of interest from concentrations ranging between 0 and1000 parts per million (ppm) in the presence of air and variousconcentrations of mercaptan (ranging from 50 to 150 ppm, benzene(ranging from 20 to 60 ppm), thiophene (ranging from 12 to 36 ppm) andtoluene (ranging from 6 to 18 ppm). The X-axis of the graph 400indicates the accuracy (standard deviation) of measuring theconcentration of H₂S across the entire 0 to 1000 ppm concentration rangeof interest in the presence of various concentrations and combinationsof the above-noted gases for an optical computing device (e.g., thedevice 300). This was done for various single ICE designs andcombinations of two or more ICE designs. As depicted, a single ICEdesign results in an accuracy ranging between about 50 ppm and about 65ppm, depending upon the specific design selected. In the example, fivedistinct single ICE designs generally corresponding to the H₂Scharacteristic were tested and the results recorded in the graph 400.

The sensitivity of the device, another key performance attribute that isvitally important to the detection limits, is also shown in the graph400 on the Y-axis. The units of sensitivity are the % change in thedetector signal output as expected over the entire H₂S concentrationrange (i.e., 0 to 1000 ppm) of interest. Regarding sensitivity, thelarger the % change, the more sensitive and desirable is the system asgreater sensitivity can enable better detectability and performancelimits, lower costs, and other important benefits. When two distinctICEs are used to detect the same characteristic of interest, however,the graph 400 unexpectedly indicates that the sensitivity of theresulting signal may increase to a level approximately two-fold better.As depicted, there were up to ten different ICE combinations that wereable to yield this dramatic improvement (while other combinations, asnoted earlier, were observed to degrade the overall performance).

The graph 400 further indicates that employing a combination of threeICEs to detect the same characteristic may increase the sensitivityapproximately three-fold over the single ICE design(s). Specifically,using a combination of three ICEs, arranged either linearly ornon-linearly, returned or otherwise reported a sensitivity of 8% changein signal over the entire H₂S concentration range of interest. Thisthree-fold improvement was seen for eight different combinations out ofall those possible amongst five different unique designs. Lastly,employing a combination of four ICEs to detect the same characteristicwas shown to increase the sensitivity of the resulting signalapproximately four-fold over the representative single ICE designs.Specifically, using a combination of four ICEs, either linearly ornon-linearly, may be able to return a sensitivity of about 11% change insignal over the entire H₂S concentration range of interest. Thisapproximate four-fold increase was obtained for five differentcombinations out of all those possible amongst the five different uniquedesigns. Accordingly, combining two or more ICEs may, in at least someembodiments, be able to increase the sensitivity of optical computingdevices, such as, but not limited to, those specifically describedherein.

Those skilled in the art will readily recognize that increases insensitivity are often accompanied by corresponding decreases in accuracyfor single ICE solutions. Thus, one single ICE design may have superiorsensitivity over another, but may generally be found to be lessaccurate. Accuracy and sensitivity are two of the most importantperformance parameters for optical computing devices, and are thusgenerally considered trade-offs to one another. The improvementdiscovered and shown in FIG. 4 was entirely unexpected. Even moreunexpected was that the sensitivity was dramatically increased in somecases without substantial trade-off in accuracy. For example, the singleICE solution exhibited accuracies ranging from 63.5 ppm to 51.7 ppm withan average of 56.4 ppm. The comparable numbers for the two ICE, threeICE, and four ICE solutions are, respectively, 52.5 to 60 ppm (56.1 ppmaverage); 53.9 to 58.6 ppm (56.1 ppm average); and 54.4 to 57.1 ppm(55.9 ppm average). Thus, in general contrast to the single ICEapplications, sensitivity may be increased using two or more ICEcomponents without experiencing a substantial or significant trade-offin accuracy.

Referring to FIG. 5, illustrated is another graph 500 indicating thedetection of H₂S (i.e., the characteristic of interest) in a sampleusing one or more ICE components. As with the graph 400 of FIG. 4, thegraph 500 and the data presented therein are used to facilitate a betterunderstanding of the present disclosure, and in no way should the theybe read to limit or define the scope of the invention. The graph 500indicates the detection of H₂S gas from concentrations ranging from 0 to1000 ppm in the presence of air and various concentrations of mercaptan(ranging from 50 to 150 ppm), benzene (ranging from 20 to 60 ppm), andtoluene (ranging from 6 to 18 ppm). The X-axis of the graph 500 depictsthe accuracy (standard deviation) of measuring the concentration of H₂Sacross the entire 0 to 1000 ppm concentration range of interest in thepresence of various concentrations and combinations of the above-notedgases for an optical computing device (e.g., the device 300). This wasdone for various single ICE designs and combinations of two or more ICEdesigns. As shown, a single ICE design can provide an accuracy rangingbetween about 43 ppm and about 49 ppm, depending upon the specificdesign selected of the five distinct designs shown.

The graph 500 further indicates that employing a combination of up tothree ICEs to detect the same characteristic may increase the accuracyas compared to the single ICE design(s). Specifically, using acombination of two ICEs, arranged either linearly or non-linearly, mayincrease accuracy down from an average of about 46 ppm to about 5.4 ppm,essentially gaining an improvement of about 8.5 times. Moreover, acombination of three ICEs may improve accuracy from an average of about46 ppm down to about 1 ppm, or essentially gaining an improvement ofabout 46 times. Accordingly, combining two or more ICEs may, in at leastsome embodiments, increase the accuracy of optical computing devices,such as, but not limited to, those specifically described herein.

As noted above, it has been typically found that increases insensitivity are generally accompanied by decreases in accuracy forsingle ICE solutions. Thus, one single ICE design may have superiorsensitivity over another, but will generally be found to be lessaccurate. Thus, the improvements obtained and depicted in FIG. 5 forthree ICE designs were entirely unexpected. Even more unexpected wasthat the accuracy, in at least some cases, increased with a reasonablysmall trade-off in sensitivity. For example, the single ICE solution asshown exhibited sensitivities ranging from 2.65 to 3.2%, with an averagearound 3%. At least three ICE combination designs improved the accuracyfrom an average of about 46 ppm down to about 1 ppm, resulting in 0.85%sensitivity. In other words, in this case accuracy was improved about46-fold with only a 3.5-fold decrease in sensitivity. Accordingly, ingeneral contrast to the single ICE applications, accuracy may beincreased without experiencing an unreasonable or significant trade-offin sensitivity.

In the exemplary cases depicted above in FIGS. 4 and 5, each of the ICEswere designed to detect the particular characteristic of interest (i.e.,H₂S). However, increases in both sensitivity and accuracy may also beobtained, in at least some cases, when at least one of the two or moreICE components is disassociated or otherwise substantially unrelated tothe characteristic of interest. For example, Table 1 below indicates thedetection of H₂S gas from concentrations ranging between 0 and 1000 ppmin the presence of air and various concentrations of mercaptan (rangingfrom 50 to 150 ppm), benzene (ranging from 20 to 60 ppm), thiophene(ranging from 12 to 36 ppm), and toluene (ranging from 6 to 18 ppm).

TABLE 1 H₂S Detection with Various ICE Accuracy (standard Totaldeviation) # ICE (ppm) Notes ICE #1 Alone (substantially 1 144Marginally predictive disassociated with H₂S) Plus ICE #2 (disassociated2 67 Predictive with H₂S) Plus ICE #3 (disassociated 3 38 Highlypredictive with H₂S)

Table 1 depicts the accuracy (standard deviation) of measuring theconcentration of H₂S across the entire 0 to 1000 ppm range usingmultiple ICE that are disassociated with H₂S. In particular, ICE #1 issubstantially disassociated with H₂S and demonstrates or otherwisereports an accuracy of 144 ppm which, as can be appreciated by thoseskilled in the art, may be considered as only slightly better than arandom guess. However, combining ICE #1 with ICE #2, which wasconsidered entirely disassociated with H₂S, unexpectedly improved theaccuracy from 144 ppm down to 67 ppm, or slightly more than two-fold.Combining ICE #1, ICE #2, and ICE #3 (where ICE #3 is also consideredentirely disassociated with H₂S) improved the accuracy even further downto 38 ppm, or slightly less than four-fold over the single ICE #1 resultof 144 ppm. Accordingly, substantial and unexpected performance can beobtained even using ICEs that are disassociated or substantiallydisassociated with the characteristic of interest. Referring now to FIG.6, with continued reference to FIG. 3, illustrated is another embodimentof the optical computing device 300, according to one or moreembodiments. As illustrated, the sample 306 may be arranged after thefirst and second ICE 302, 304, such that the electromagnetic radiation310 is directly received by the first and second ICE 302, 304 andoptically interacted light 602 is thereafter directed to the sample 306.As depicted, the detector 316 still receives optically interacted light314, albeit from the sample 306 instead of from the first and second ICE302, 304. Accordingly, it matters not in what order the sample 306 andfirst and second ICE 302, 304 optically interact with theelectromagnetic radiation 310, as long as each component is able to doso before the resulting optically interacted light 314 (i.e., includingoptical interaction with both the sample 306 and the first and secondICE 302, 304) is eventually directed to the detector 316. Moreover, itwill be appreciated that while FIG. 6 shows the electromagneticradiation 310 passing through the first and second ICE 302, 304 in orderto optically interact with the sample 306, the electromagnetic radiation310 could equally be reflected off the first and second ICE 302, 304toward the sample 306. Likewise, while FIG. 6 shows the opticallyinteracted light 602 passing through the sample 306, the opticallyinteracted light 602 could equally be reflected off of the sample 306and subsequently detected by the detector 316, without departing fromthe scope of the disclosure. Furthermore, embodiments are contemplatedherein that include one or more optional beam splitters, mirrors, andthe like in order to allow the electromagnetic radiation 310 tooptically interact with both the sample 306 and first and second ICE302, 304, without departing from the scope of the disclosure. Indeed,one or more optional beam splitters, mirrors, and the like may be usedin conjunction with any of the exemplary embodiments disclosed herein,without departing from the scope of the disclosure.

Consequently, it should be understood that even though theelectromagnetic radiation 310 may optically interact with the sample 306before reaching the first and second ICE 302, 304, the first and secondICE 302, 304 nonetheless are considered to have optically interactedwith the electromagnetic radiation 310, albeit subsequent to the sample306. Likewise, even though the electromagnetic radiation 310 mayoptically interact with the first and second ICE 302, 304 beforereaching the sample 306, the sample 306 nonetheless is considered tohave optically interacted with the electromagnetic radiation 310, albeitsubsequent to the first and second ICE 302, 304. Furthermore,embodiments are contemplated herein where the first ICE 302 is arrangedon one side of the sample 306, and the second ICE 304 is arranged on theopposite side of the sample 306. As a result, the electromagneticradiation 310 may optically interact with the first ICE 302 prior tooptically interacting with the sample 306, and subsequently opticallyinteracting with the second ICE 304. The resulting optically interactedlight 314 directed to the detector 316 may nonetheless be similar toembodiments where the first and second ICE 302, 304 are arranged eitherbefore or after the sample 306. Moreover, it will be appreciated thatany and all of the embodiments disclosed herein may include any of theexemplary variations discussed herein, such as arranging the sample 306before or after the ICE 302, 304, or arranging the ICE 302, 304 inlinear or non-linear configurations. While not particularly disclosed,several variations of the embodiments disclosed herein will equally fallwithin the scope of the disclosure.

Referring now to FIG. 7, illustrated is another embodiments of anoptical computing device 700 disclosed herein, according to one or moreembodiments. The device 700 may be best understood with reference toFIGS. 3 and 6, where like numerals indicate like elements that will notbe described again in detail. The device 700 may include a first ICE 702and a second ICE 704. The first and second ICE 702, 704 may be similarin construction to the ICE 100 described above with reference to FIG. 1,and configured to be either associated or disassociated with aparticular characteristic of the sample, such as is described above withreference to the first and second ICE 302, 304 of FIGS. 3 and 6.

As illustrated, the first and second ICE 702, 704 may be coupledtogether to form a monolithic structure, but in other embodiments may bearranged in series, as briefly discussed above, without departing fromthe scope of the disclosure. Moreover, the first and second ICE 702, 704may be arranged to receive sample-interacted light 312, as depicted, butmay equally be arranged antecedent to the sample 306, as generallydescribed above with reference to FIG. 6. In one embodiment, the firstICE 702 may be smaller than the second ICE 704 such that a portion ofthe sample-interacted light 312 (or portion of the electromagneticradiation 310, in the event the sample 306 is arranged on the other sideof the first and second ICE 702, 704) passes through only the second ICE704 and generates a first beam of optically interacted light 314 a, andanother portion of the sample-interacted light 312 passes through boththe first and second ICE 702, 704 and thereby generates a second beam ofoptically interacted light 314 b.

The first and second beams of optically interacted light 314 a,b may bedirected to the detector 316, which may be a split or differentialdetector, having a first detector portion 316 a and a second detectorportion 316 b. In other embodiments, however, the detector 316 may be adetector array, as known in the art, without departing from the scope ofthe disclosure. In operation, the first detector portion 316 a may beconfigured to receive the first beam of optically interacted light 314 aand generate a first signal 706 a, and the second detector portion 316 bmay be configured to receive the second beam of optically interactedlight 314 b and generate a second signal 706 b. In some embodiments, thedetector 316 may be configured to computationally combine the first andsecond signals 706 a,b in order to determine the characteristic of thesample, for example when using a differential detector or quad-detector.In other embodiments, the first and second signals 706 a,b may betransmitted to or otherwise received by a signal processor 708communicably coupled to the detector 316 and configured tocomputationally combine the first and second signals 706 a,b in order todetermine the characteristic of the sample. In some embodiments, thesignal processor 708 may be a computer including a non-transitorymachine-readable medium, as generally described above.

In at least one embodiment, the device 700 may further include thesecond detector 318 arranged to receive and detect reflected opticallyinteracted light 320, as generally described above with reference toFIG. 3. As described above, the second detector 318 may be used todetect electromagnetic radiating deviations exhibited by theelectromagnetic radiation source 308, and thereby normalize the signaloutput of the first detector 316. In at least one embodiment, the seconddetector 318 may be communicably coupled to the signal processor 708such that the compensating signal 322 indicative of electromagneticradiating deviations may be provided or otherwise conveyed thereto. Thesignal processor 708 may then be configured to computationally combinethe compensating signal 322 with the first and second signals 706 a,b,and thereby provide a more accurate determination of the characteristicof the sample. In one embodiment, for example, the compensating signal322 is combined with the first and second signals 706 a,b via principalcomponent analysis techniques such as, but not limited to, standardpartial least squares which are available in most statistical analysissoftware packages (e.g., XL Stat for MICROSOFT® EXCEL®; the UNSCRAMBLER®from CAMO Software and MATLAB® from MATHWORKS®).

Referring now to FIG. 8, with continued reference to FIG. 7, illustratedis another optical computing device 800, according to one or moreembodiments. The device 800 may be somewhat similar to the opticalcomputing device 700 described with reference to FIG. 7, therefore thedevice 800 may be best understood with reference thereto, where likenumerals indicate like elements. The device 800 may include a first ICE802 and a second ICE 804 similar in construction to the ICE 100described above with reference to FIG. 1, and configured to be eitherassociated or disassociated with a particular characteristic of thesample 306, such as is described above with reference to the first andsecond ICE 302, 304 of FIGS. 3 and 6.

As illustrated, the first and second ICE 802, 804 may be arrangedgenerally parallel relative to one another and configured to receive thesample-interacted light 312. As with prior embodiments, however, thefirst and second ICE 802, 804 may equally be arranged antecedent to thesample 306, as generally described above with reference to FIG. 6,without departing from the scope of the disclosure. In operation, thefirst ICE 802 may receive a portion of the sample-interacted light 312(or portion of the electromagnetic radiation 310, in the event thesample 306 is arranged on the other side of the first and second ICE802, 804) and thereby generate the first beam of optically interactedlight 314 a. The second ICE 804 may be configured to receive anotherportion of the sample-interacted light 312 and thereby generate thesecond beam of optically interacted light 314 b. The first and secondbeams of optically interacted light 314 a,b may be directed to thedetector 316 to generate the first signal 706 a and the second signal706 b corresponding to the first and second beams of opticallyinteracted light 314 a,b, respectively.

The first detector portion 316 a may be configured to receive the firstbeam of optically interacted light 314 a and generate the first signal706 a, and the second detector portion 316 b may be configured toreceive the second beam of optically interacted light 314 b and generatethe second signal 706 b. In some embodiments, the detector 316 may beconfigured to computationally combine the first and second signals 706a,b in order to determine the characteristic of the sample. In otherembodiments, however, the first and second signals 706 a,b may bereceived by a signal processor 708 communicably coupled to the detector316 and configured to computationally combine the first and secondsignals 706 a,b in order to determine the characteristic of the sample.

In some embodiments, the detector 316 is a single detector butconfigured to time multiplex the first and second beams of opticallyinteracted light 314 a,b. For example, the first ICE 802 may beconfigured to direct the first beam of optically interacted light 314 atoward the detector 316 at a first time T1, and the second ICE 804 maybe configured to direct the second beam of optically interacted light314 b toward the detector 316 at a second time T2, where the first andsecond times T1, T2 are distinct time periods that do not spatiallyoverlap. Consequently, the detector 316 receives at least two distinctbeams of optically interacted light 314 a,b, which may becomputationally combined by the detector 316 in order to provide anoutput in the form of a voltage that corresponds to the characteristicof the sample. In one or more embodiments, in order to provide the firstand second times T1, T2, the device 800 may include more than oneelectromagnetic radiation source 308. In other embodiments, theelectromagnetic radiation source 308 may be pulsed in order to providethe first and second times T1, T2. In yet other embodiments, each ICE802, 804 may be mechanically positioned to interact with theelectromagnetic radiation beam at two distinct times. In yet otherembodiments, the electromagnetic radiation beam may be deflected, ordiffracted to interact with the two different ICE elements at times T1and T2. Moreover, it will be appreciated that more than the first andsecond ICE 802, 804 may be used without departing from the scope of thisembodiment, and the detector 316 may therefore be configured to timemultiplex each additional beam of optically interacted light to providethe cumulative voltage corresponding to the characteristic of thesample.

Referring now to FIG. 9a , illustrated is another optical computingdevice 900, according to one or more embodiments. The device 900 may besomewhat similar to the optical computing devices 700, 800 describedwith reference to FIGS. 7 and 8 and therefore the device 900 may be bestunderstood with reference thereto, where like numerals indicate likeelements. The device 900 may include at least two ICE, including a firstICE 902 a and a second ICE 902 b, and may further include one or moreadditional ICE 902 n. Each ICE 902 a-n may be similar in construction tothe ICE 100 described above with reference to FIG. 1, and configured tobe either associated or disassociated with a particular characteristicof the sample 306, such as is described above with reference to thefirst and second ICE 302, 304 of FIGS. 3 and 6. The device 900 mayfurther include a plurality of detectors, such as a first detector 316a, a second detector 316 b, and one or more additional detectors 316 n.

As illustrated in FIG. 9a , the first, second, and additional ICE 902a-n may each be arranged in series relative to one another andconfigured to optically interact with the electromagnetic radiation 312either through the sample 306 or through varying configurations ofreflection and/or transmission between adjacent ICE 902 a-n. In theembodiment specifically depicted, the first ICE 902 a may be arranged toreceive the sample-interacted light 312 from the sample 306. As withprior embodiments, however, the first ICE 902 a may equally be arrangedantecedent to the sample 306, as generally described above withreference to FIG. 6, and therefore optically interact with theelectromagnetic radiation 310. The first ICE 902 a may be configured totransmit a first optically interacted light 904 a to the first detector316 a and simultaneously convey reflected optically interacted light 906toward the second ICE 902 b. The second ICE 902 b may be configured toconvey a second optically interacted light 904 b via reflection towardthe second detector 316 b, and simultaneously transmit additionaloptically interacted light 908 toward the additional ICE 902 n. Theadditional ICE 902 n may be configured to convey an additional opticallyinteracted light 904 n via reflection toward the additional detector 316n. Those skilled in the art will readily recognize numerous alternativeconfigurations of the first, second, and additional ICE 902 a-n, withoutdeparting from the scope of the disclosure. For example, reflection ofoptically interacted light from a particular ICE may be replaced withtransmission of optically interacted light, or alternativelyconfigurations may include the use of mirrors or beam splittersconfigured to direct the electromagnetic radiation 310 (orsample-interacted light 312) to each of the first, second, andadditional ICE 902 a-n.

The first, second, and additional detectors 316 a-n may be configured todetect the first, second, and additional optically interacted light 904a-n, respectively, and thereby generate a first signal 706 a, a secondsignal 706 b, and one or more additional signals 706 n, respectively. Insome embodiments, the first, second, and additional signals 706 a-n maybe received by a signal processor 708 communicably coupled to eachdetector 316 a-n and configured to computationally combine the first,second, and additional signals 706 a-n in order to determine thecharacteristic of the sample 306.

Accordingly, any number of ICE may be arranged or otherwise used inseries in order to determine the characteristic of the sample 306. Insome embodiments, each of the first, second, and additional ICE 902 a-nmay be specially-designed to detect the particular characteristic ofinterest or otherwise be configured to be associated therewith. In otherembodiments, however, one or more of the first, second, and additionalICE 902 a-n may be configured to be disassociated with the particularcharacteristic of interest, and/or otherwise may be associated with anentirely different characteristic of the sample 306. In yet otherembodiments, each of the first, second, and additional ICE 902 a-n maybe configured to be disassociated with the particular characteristic ofinterest, and otherwise may be associated with an entirely differentcharacteristic of the sample 306.

In at least one embodiment, the device 900 may further include thesecond detector 318 arranged to receive and detect optically interactedlight 320, as generally described above with reference to FIG. 3. Thesecond detector 318 may again be used to detect electromagneticradiating deviations exhibited by the electromagnetic radiation source308 and output the compensating signal 322 indicative of electromagneticradiating deviations. In at least one embodiment, the second detector318 may be communicably coupled to the signal processor 708 such thatthe compensating signal 322 may be provided or otherwise conveyedthereto in order to normalize the signals 706 a-n produced by thedetectors 316 a-n. The signal processor 708 may then be configured tocomputationally combine the compensating signal 322 with the signals 706a-n, and thereby provide a more accurate determination of thecharacteristic of the sample.

Referring now to FIG. 9b , illustrated is an alternative configurationof the optical computing device 900, according to one or moreembodiments. In FIG. 9b , a series of beam splitters 910 a, 910 b, 910 nmay be used to separate or otherwise redirect the sample-interactedlight 312 As depicted, each beam splitter 910 a-n may be configured toproduce and direct a respective beam 912 a, 912 b, 912 n ofsample-interacted light 312 toward a corresponding ICE 902 a-n. Each ICE902 a-n may then be configured to transmit its respective opticallyinteracted light 904 a-n toward a corresponding detector 316 a-n,thereby generating the first, second, and additional signals 706 a-n,respectively. The first, second, and additional signals 706 a-n may thenbe received by a signal processor 708 communicably coupled to eachdetector 316 a-n and configured to computationally combine the first,second, and additional signals 706 a-n in order to determine thecharacteristic of the sample 306.

In some embodiments, the second detector 318 may again be used to detectelectromagnetic radiating deviations exhibited by the electromagneticradiation source 308, and thereby normalize the signals 706 a-n producedby the detectors 316 a-n. The second detector 318 may be communicablycoupled to the signal processor 708 such that the compensating signal322 indicative of electromagnetic radiating deviations may be providedor otherwise conveyed thereto. The signal processor 708 may then beconfigured to computationally combine the compensating signal 322 withthe signals 706 a-n, and thereby normalize the signals 706 a-n andprovide a more accurate determination of the characteristic of thesample 306.

Referring now to FIG. 9c , illustrated is yet another alternativeconfiguration of the optical computing device 900, according to one ormore embodiments. As illustrated in FIG. 9c , the sample-interactedlight 312 may be fed into or otherwise provided to, for example, anoptical light pipe 914. The optical light pipe may be configured toconvey the sample-interacted light 312 individually to each ICE 902 a-n.In some embodiments, the optical light pipe 914 may be a fiber opticbundle having a plurality of corresponding conveying bundles. Inoperation, a first bundle 914 a may be configured to conveysample-interacted light 312 to the first ICE 902 a in order to generatethe first optically interacted light 904 a; a second bundle 914 b may beconfigured to convey sample-interacted light 312 to the second ICE 902 bin order to generate the second optically interacted light 904 b; and anadditional bundle 914 n may be configured to convey sample-interactedlight 312 to the additional ICE 902 n in order to generate theadditional optically interacted light 904 n. At least one additionalbundle 914 x may be configured to convey sample-interacted light 312 tothe second detector 318 in order to generate the compensating signal322. Processing of the resulting optically interacted light 904 a-n andsignals 706 a-n may be accomplished as generally described above.

It should be noted that the use of optical light pipes, such as theoptical light pipe 914 discussed above, may be employed in any of thevarious embodiments discussed herein, without departing from the scopeof the disclosure. Use a light pipe, or a variation thereof, may proveadvantageous in that the light pipe substantially removes interferentobstruction that may otherwise contaminate the sample-interacted light312 provided to the various ICEs.

Referring now to FIG. 10, illustrated is another optical computingdevice 1000, according to one or more embodiments. The device 1000 maybe somewhat similar to the optical computing device 300 described withreference to FIGS. 3 and 6 and therefore the device 1000 may be bestunderstood with reference thereto, where like numerals indicate likeelements. The device 1000 may include a movable assembly 1002 having atleast two ICEs associated therewith. As illustrated, the movableassembly 1002 may be characterized at least in one embodiment as arotating disc 1003, wherein the at least two ICEs are radially disposedfor rotation therewith. Alternatively, the movable assembly 1002 may becharacterized as a linear array 1005, wherein the at least two ICEs arelaterally offset from each other. FIG. 10 illustrates correspondingfrontal views of the rotating disc 1003 and the linear array 1005, eachof which is described in more detail below.

Those skilled in the art will readily recognize, however, that themovable assembly 1002 may be characterized as any type of movableassembly configured to sequentially align at least one detector withoptically interacted light and/or one or more ICE. For example, themovable assembly 1002 may include such apparatus or devices as, but notlimited to, an oscillating or translating linear array of ICE, one ormore scanners, one or more beam deflectors, combinations thereof, or thelike. In other embodiments, the movable assembly 1002 may becharacterized as an assembly including a plurality of optical lightpipes (e.g., fiber optics) configured to perform optical beam splittingto a fixed array of ICE and/or detectors.

The rotating disc 1003 may include a first ICE 1004 a, a second ICE 1004b, a third ICE 1004 c, a fourth ICE 1004 d, and a fifth ICE 1004 earranged about or near the periphery of the rotating disc 1003 andcircumferentially-spaced from each other. Each ICE 1004 a-e may besimilar in construction to the ICE 100 described above with reference toFIG. 1, and configured to be either associated or disassociated with aparticular characteristic of the sample 306, such as is described abovewith reference to the first and second ICE 302, 304 of FIGS. 3 and 6. Invarious embodiments, the rotating disc 1003 may be rotated at afrequency of about 0.1 RPM to about 30,000 RPM. In operation, therotating disc 1003 may rotate such that the individual ICEs 1004 a-e mayeach be exposed to or otherwise optically interact with thesample-interacted light 312 for a distinct brief period of time. In atleast one embodiment, however, the movable assembly 1002 may be arrangedantecedent to the sample 306, as generally described above withreference to FIG. 6, such that the individual ICEs 1004 a-e of therotating disc 1003 may be exposed to or otherwise optically interactwith the electromagnetic radiation 310 for a brief period of time. Uponoptically interacting with the sample-interacted light 312 (or theelectromagnetic radiation 310, in the event the sample 306 is arrangedsubsequent to the movable assembly 1002), each ICE 1004 a-e may beconfigured to produce optically interacted light, for example, a firstbeam of optically interacted light 1006 a, a second beam of opticallyinteracted light 1006 b, a third beam of optically interacted light 1006c, a fourth beam of optically interacted light 1006 d, and a fifth beamof optically interacted light 1006 e, respectively.

Each beam of optically interacted light 1006 a-e may be detected by thedetector 316 which may be configured to time multiplex the opticallyinteracted light 1006 a-e between the individually-detected beams. Forexample, the first ICE 1004 a may be configured to direct the first beamof optically interacted light 1006 a toward the detector 316 at a firsttime T1, the second ICE 1004 b may be configured to direct the secondbeam of optically interacted light 1006 b toward the detector 316 at asecond time T2, and so on until the fifth ICE 1004 e may be configuredto direct the fifth beam of optically interacted light 1006 e toward thedetector 316 at a fifth time T5. Consequently, the detector 316 receivesat least five distinct beams of optically interacted light 1006 a-e,which may be computationally combined by the detector 316 in order toprovide an output in the form of a voltage that corresponds to thecharacteristic of the sample. In some embodiments, these beams ofoptically interacted light 1006 a-e may be averaged over an appropriatetime domain (e.g., about 1 millisecond to about 1 hour) to moreaccurately determine the characteristic of the sample 306.

In one or more embodiments, at least one of the ICE 1004 a-e may be aneutral element configured to simply pass the sample-interacted light312 (or the electromagnetic radiation 310, in the event the sample 306is arranged subsequent to the movable assembly 1002) withoutoptical-interaction. As a result, the neutral element may be configuredto provide a neutral signal to the detector 316 that may besubstantially similar to the compensating signal 322 as described abovewith reference to FIG. 3. In operation, the detector 316 may detect theneutral signal, which may be indicative of radiating deviations stemmingfrom the electromagnetic radiation source 308. The detector 316 may thenbe configured to computationally combine the compensating signal 322with the remaining beams of optically interacted light 1006 a-e tocompensate for electromagnetic radiating deviations stemming from theelectromagnetic radiation source 308, and thereby provide a moreaccurate determination of the characteristic of the sample.

As will be appreciated, any number of ICE 1004 a-e may be radiallyarranged on the rotating disc 1003 in order to determine thecharacteristic of the sample 306. In some embodiments, each of the ICE1004 a-e may be specially-designed to detect or otherwise configured tobe associated with the particular characteristic of interest. In otherembodiments, however, one or more of the ICE 1004 a-e may be configuredto be disassociated with the particular characteristic of interest, andotherwise may be associated with an entirely different characteristic ofthe sample 306. Advantages of this approach may include the ability toanalyze multiple analytes using a single optical computing device andthe opportunity to assay additional analytes simply by adding additionalICEs to the rotating disc 1003.

The linear array 1005 may also include the first, second, third, fourth,and fifth ICE 1004 a-e, although aligned linearly as opposed toradially. The linear array 1005 may be configured to oscillate orotherwise translate laterally such that each ICE 1004 a-e is exposed toor otherwise able to optically interact with the sample-interacted light312 for a distinct brief period of time. Similar to the rotating disc1003, the linear array 1005 may be configured to produce opticallyinteracted light 1006 a-e. Moreover, as with the rotating disc 1003embodiment, the detector 316 may be configured to time multiplex theoptically interacted light 1006 a-e between the individually-detectedbeams and subsequently provide an output in the form of a voltage thatcorresponds to the characteristic of the sample. Even further, at leastone of the ICE 1004 a-e may be a neutral element configured to provide aneutral signal to the detector 316 that may be computationally combinedwith the remaining beams of optically interacted light 1006 a-e tocompensate for electromagnetic radiating deviations stemming from theelectromagnetic radiation source 308.

As will be appreciated, any number of ICE 1004 a-e may be arranged onthe linear array 1005 in order to determine the characteristic of thesample 306. In some embodiments, each of the ICE 1004 a-e may bespecially-designed to detect or otherwise configured to be associatedwith the particular characteristic of interest. In other embodiments,however, one or more of the ICE 1004 a-e may be configured to bedisassociated with the particular characteristic of interest, andotherwise may be associated with an entirely different characteristic ofthe sample 306. In yet other embodiments, each of the one or more ICE1004 a-e may be configured to be disassociated with the particularcharacteristic of interest, and otherwise may be associated with anentirely different characteristic of the sample 306.

Referring now to FIG. 11, with continued reference to FIG. 10,illustrated is another exemplary optical computing device 1100,according to one or more embodiments. The device 1100 may be somewhatsimilar to the device 1000 of FIG. 10, and therefore may be bestunderstood with reference thereto where like numerals indicate likeelements. The device 1100 may include a movable assembly 1102 similar insome respects to the movable assembly 1002 of FIG. 10. For example, FIG.11 illustrates an alternative embodiment of a rotating disc 1103. Thefilter wheel 1103 in FIG. 11, however, may include multipleradially-offset rows or arrays of ICE, such as a first radial array 1104a, a second radial array 1104 b, and a third radial array 1104 c. Whilethree radial arrays 1104 a-c are shown in FIG. 11, it will beappreciated that the filter wheel 1103 may include more or less thanthree radially-offset radial arrays 1104 a-c, without departing from thescope of the disclosure.

Each radially-offset radial array 1104 a-c may include a plurality ofICEs 1106 circumferentially-spaced from each other. Each ICE 1106 may besimilar in construction to the ICE 100 described above with reference toFIG. 1, and configured to be either associated or disassociated with aparticular characteristic of the sample 306, such as is described abovewith reference to the first and second ICE 302, 304 of FIGS. 3 and 6. Inoperation, the filter wheel 1103 rotates such that the one or more ICEs1106 may each be exposed to or otherwise optically interact with thesample-interacted light 312 for a distinct brief period of time. In atleast one embodiment, however, the filter wheel 1103 may be arrangedantecedent to the sample 306, as generally described above withreference to FIG. 6, and therefore the one or more ICEs 1106 may beexposed to or otherwise optically interact with the electromagneticradiation 310 for a brief period of time. Upon optically interactingwith the sample-interacted light 312 (or the electromagnetic radiation310, in the event the sample 306 is arranged subsequent to the filterwheel 1103), each ICE 1106 may be configured to produce an individual orcombined beam of optically interacted light 1108 directed toward thedetector 316.

Each individual or combined beam of optically interacted light 1108 maybe detected by the detector 316 which may be configured to timemultiplex the optically interacted light 1108 between the combined orindividually-detected beams. Consequently, the detector 316 receives aplurality of beams of optically interacted light 1108 which may becomputationally combined by the detector 316 in order to provide anoutput in the form of a voltage that corresponds to the characteristicof the sample. Moreover, one or more of the ICE 1106 may be a neutralelement configured to provide a neutral signal to the detector 316, asgenerally described above with reference to FIG. 10. The neutral signalmay be indicative of radiating deviations stemming from theelectromagnetic radiation source 308, and the detector 316 may beconfigured to computationally combine the neutral signal with theremaining beams of optically interacted light 1108 to compensate forelectromagnetic radiating deviations stemming from the electromagneticradiation source 308, and thereby provide a more accurate determinationof the characteristic of the sample.

While the various embodiments disclosed herein provide that theelectromagnetic radiation source 308 is used to provide electromagneticradiation that optically interacts with the at least two ICEs, thoseskilled in the art will readily recognize that electromagnetic radiationmay be derived from the sample 306 itself, and otherwise derivedindependent of the electromagnetic radiation source 308. For example,various substances naturally radiate electromagnetic radiation that isable to optically interact with the at least two ICEs. In someembodiments, the sample 306 may be a blackbody radiating substanceconfigured to radiate heat that may optically interact with the at leasttwo ICEs. In other embodiments, the sample 306 may be radioactive orchemo-luminescent and, therefore, radiate electromagnetic radiation thatis able to optically interact with the at least two ICEs. In yet otherembodiments, the electromagnetic radiation may be induced from thesample 306 by being acted upon mechanically, magnetically, electrically,combinations thereof, or the like. For instance, in at least oneembodiment, a voltage may be placed across the sample 306 in order toinduce the electromagnetic radiation. As a result, embodiments arecontemplated herein where the electromagnetic radiation source 308 isomitted from the particular optical computing device.

Therefore, the present invention is well adapted to attain the ends andadvantages mentioned as well as those that are inherent therein. Theparticular embodiments disclosed above are illustrative only, as thepresent invention may be modified and practiced in different butequivalent manners apparent to those skilled in the art having thebenefit of the teachings herein. Furthermore, no limitations areintended to the details of construction or design herein shown, otherthan as described in the claims below. It is therefore evident that theparticular illustrative embodiments disclosed above may be altered,combined, or modified and all such variations are considered within thescope and spirit of the present invention. While compositions andmethods are described in terms of “comprising,” “containing,” or“including” various components or steps, the compositions and methodscan also “consist essentially of” or “consist of” the various componentsand steps. All numbers and ranges disclosed above may vary by someamount. Whenever a numerical range with a lower limit and an upper limitis disclosed, any number and any included range falling within the rangeis specifically disclosed. In particular, every range of values (of theform, “from about a to about b,” or, equivalently, “from approximately ato b,” or, equivalently, “from approximately a-b”) disclosed herein isto be understood to set forth every number and range encompassed withinthe broader range of values. Also, the terms in the claims have theirplain, ordinary meaning unless otherwise explicitly and clearly definedby the patentee. Moreover, the indefinite articles “a” or “an,” as usedin the claims, are defined herein to mean one or more than one of theelement that it introduces. If there is any conflict in the usages of aword or term in this specification and one or more patent or otherdocuments that may be incorporated herein by reference, the definitionsthat are consistent with this specification should be adopted.

What is claimed is:
 1. A method of determining a characteristic of asample, comprising: optically interacting an electromagnetic radiationsource with the sample to form input light for at least two integratedcomputational elements, wherein a first one of the at least twointegrated computational elements comprises a first plurality of layersof material and a second one of the at least two integratedcomputational elements comprises a second plurality of layers ofmaterial different from the first plurality of layers of material, thefirst and second pluralities of layers of material being disposedaccording to the characteristic of the sample; producing opticallyinteracted light from the at least two integrated computationalelements, wherein the first and second plurality of layers of materialare selected so that an intensity of the optically interacted light isproportional to a dot product between an input light spectrum vector anda regression vector associated with the characteristic of the sample;receiving with at least one detector the optically interacted light fromthe at least two integrated computational elements, thereby generating afirst signal and a second signal; and computationally combining thefirst and second signals to determine the characteristic of the sample.2. The method of claim 1, wherein the at least one detectorcomputationally combines the first and second signals.
 3. The method ofclaim 1, wherein the at least one detector is a first detector, themethod further comprising: detecting with a second detectorelectromagnetic radiation from the electromagnetic radiation source;generating a third signal with the second detector, the third signalbeing indicative of electromagnetic radiating deviations; receiving thethird signal with a signal processor communicably coupled to the firstand second detectors; and computationally combining the third signalwith the first and second signals to normalize the first and secondsignals.
 4. The method of claim 1, further comprising rotating the atleast two first and second integrated computational elements within amovable assembly configured for rotation, the at least two integratedcomputational elements being radially disposed within the movableassembly.
 5. The method of claim 4, further comprising: opticallyinteracting the electromagnetic radiation source with at least oneneutral element radially disposed within the movable assembly forrotation therewith; and producing a compensating signal indicative ofradiating deviations of the electromagnetic radiation source.
 6. Themethod of claim 5, further comprising: receiving with the at least onedetector the compensating signal; and computationally combining thecompensating signal with the first and second signals in order tocompensate for electromagnetic radiating deviations.
 7. The method ofclaim 1, further comprising oscillating the at least two first andsecond integrated computational elements as arranged on a linear array.8. A method of determining a characteristic of a sample, comprising:optically interacting an electromagnetic radiation source with thesample to form input light for at least two integrated computationalelements, wherein a first one of the at least two integratedcomputational elements comprises a first plurality of layers of materialand a second one of the at least two integrated computational elementscomprises a second plurality of layers of material different from thefirst plurality of layers of material, the first and second pluralitiesof layers of material being disposed according to the characteristic ofthe sample; producing optically interacted light from the at least twointegrated computational elements, wherein the first and secondplurality of layers of material are selected so that an intensity of theoptically interacted light is proportional to a dot product between aninput light spectrum vector and a regression vector associated with thecharacteristic of the sample; and receiving with at least one detectorthe optically interacted light from the at least two integratedcomputational elements, thereby generating a first signal correspondingto the characteristic of the sample.
 9. The method of claim 8, furthercomprising: detecting with a second detector electromagnetic radiationfrom the electromagnetic radiation source; and generating a secondsignal indicative of electromagnetic radiating deviations with thesecond detector.
 10. The method of claim 9, further comprising:receiving the first and second signals with a signal processorcommunicably coupled to the first and second detectors; andcomputationally combining the first and second signals to normalize thefirst signal.
 11. A method of determining a characteristic of a sample,comprising: optically interacting electromagnetic radiation radiatedfrom the sample with at least two integrated computational elements,wherein a first one of the at least two integrated computationalelements comprises a first plurality of layers of material and a secondone of the at least two integrated computational elements comprises asecond plurality of layers of material different from the firstplurality of layers of material, the first and second pluralities oflayers of material disposed according to a characteristic of the sample;producing optically interacted light from the at least two integratedcomputational elements, the at least two integrated computationalelements each being configured to be associated with the characteristicof the sample, wherein the first and second plurality of layers ofmaterial are selected so that an intensity of the optically interactedlight is proportional to a dot product between a spectrum vector of theelectromagnetic radiation radiated from the sample and a regressionvector associated with the characteristic of the sample; and receivingwith at least one detector the optically interacted light from the atleast two integrated computational elements, thereby generating a firstsignal corresponding to the characteristic of the sample.
 12. The methodof claim 11, further comprising acting upon the sample mechanically,magnetically, or electrically in order to emit the electromagneticradiation from the sample.